Gas turbine engines with heat recovery systems

ABSTRACT

A gas turbine engine includes a fan located at a forward portion of the gas turbine engine, a compressor section and a turbine section arranged in serial flow order. The compressor section and the turbine section together define a core airflow path. A rotary member is rotatable with at least a portion of the compressor section and with at least a portion of the turbine section. An outlet guide vane assembly includes multiple outlet guide vanes located in an exhaust airflow path downstream of the turbine section. The multiple outlet guide vanes being spaced-apart circumferentially from each other over an angular range of about 360 degrees, and each multiple outlet guide vane defining a radial extent. At least one of the multiple outlet guide vanes includes a cold fluid passageway extending at least partially radially therethrough through which a fluid coolant flows and another of the multiple guide vanes includes a heated fluid passageway extending at least partially radially therethrough through which the fluid coolant flows and receives heat from exhaust airflow from the core airflow path.

BACKGROUND Field

The present specification generally relates to gas turbine engines and,more specifically, to gas turbine engines that include heat recoverysystems.

Technical Background

Gas turbine engines are frequently used as part of aircraft propulsionsystems. Gas turbine engines may include a compressor section, acombustion section, a turbine section and an exhaust section. Air isprovided by a fan to the compressor section where the air is compressedand delivered to the combustion section. In the combustion section, theair is mixed with fuel and then burned. The combustion gases are thendelivered to the turbine section, which drives the turbine sectionbefore delivering the combustion gases to the exhaust section.

During operation, temperatures within the gas turbine engines may beelevated. In order to manage the increases in temperature of the gasturbine engines, various cooling systems may be provided that are usedto remove thermal energy from various components of the gas turbineengines. This heat may be used by other engine systems in a beneficialway.

SUMMARY

According to an embodiment of the present disclosure, a gas turbineengine includes a fan located at a forward portion of the gas turbineengine, a compressor section and a turbine section arranged in serialflow order. The compressor section and the turbine section togetherdefine a core airflow path. A rotary member is rotatable with at least aportion of the compressor section and with at least a portion of theturbine section. An outlet guide vane assembly includes multiple outletguide vanes located in an exhaust airflow path downstream of the turbinesection. The multiple outlet guide vanes being spaced-apartcircumferentially from each other over an angular range of about 360degrees, and each multiple outlet guide vane defining a radial extent.At least one of the multiple outlet guide vanes includes a cold fluidpassageway extending at least partially radially therethrough throughwhich a fluid coolant flows and another of the multiple guide vanesincludes a heated fluid passageway extending at least partially radiallytherethrough through which the fluid coolant flows and receives heatfrom exhaust airflow from the core airflow path. A “fluid” is intendedto mean a liquid or gas, or a substance that exhibits properties of botha gas and a liquid (i.e., supercritical fluid).

According to another embodiment of the present disclosure, a methodincludes removably attaching an outlet guide vane assembly to a turbinerear frame of a gas turbine engine. The outlet guide vane assemblyincludes multiple outlet guide vanes located in an exhaust airflow pathdownstream of the turbine section. The multiple outlet guide vanes beingspaced-apart circumferentially from each other over an angular range ofabout 360 degrees, and each multiple outlet guide vane defining a radialextent. At least one of the multiple outlet guide vanes includes a coldfluid passageway extending at least partially radially therethroughthrough which a fluid coolant flows and another of the multiple guidevanes comprises a heated fluid passageway extending at least partiallyradially therethrough through which the fluid coolant flows and receivesheat from exhaust airflow from a core airflow path. The fluid coolant isdelivered through the cold fluid passageway and then the heated fluidpassageway. The fluid coolant receives heat from exhaust airflow fromthe core airflow path as the fluid coolant is directed through theheated fluid passageway.

According to another embodiment of the present disclosure, a gas turbineengine includes a compressor section and a turbine section arranged inserial flow order. The compressor section and the turbine sectiontogether define a core airflow path. A rotary member is rotatable withat least a portion of the compressor section and with at least a portionof the turbine section. A turbine rear frame includes first outlet guidevanes located in an exhaust airflow path downstream of the turbinesection. The first outlet guide vanes being spaced-apartcircumferentially from each other over an angular range of about 360degrees, and each first outlet guide vane defining a radial extent. Anoutlet guide vane assembly includes second outlet guide vanes located inthe exhaust airflow path adjacent the first outlet guide vanes. Thesecond outlet guide vanes are spaced-apart circumferentially from eachother over an angular range of about 360 degrees, and each second outletguide vane defining a radial extent. One or both of the first outletguide vanes and the second outlet guide vanes is turning therebyaltering a flow direction of exhaust airflow from the exhaust airflowpath.

According to another embodiment of the present disclosure, a gas turbineengine includes a fan located at a forward portion of the gas turbineengine, a compressor section and a turbine section arranged in serialflow order. The compressor section and the turbine section togetherdefine a core airflow path. A rotary member is rotatable with at least aportion of the compressor section and with at least a portion of theturbine section. An outlet guide vane assembly includes multiple outletguide vanes located in an exhaust airflow path downstream of the turbinesection. The multiple outlet guide vanes being spaced-apartcircumferentially from each other over an angular range of about 360degrees, and each multiple outlet guide vane defining a radial extent.One or more outlet guide vane includes a surface enhancement featurethat increases a surface area of a side surface of the outlet guidevane.

Additional features, embodiments and advantages of the gas turbineengines and methods of their use described herein will be set forth inthe detailed description which follows, and in part will be readilyapparent to those skilled in the art that such features, embodiments andadvantages are contemplated and considered within the scope of thedisclosure, based on the teachings disclosed hereupon.

It is to be understood that both the foregoing general description andthe following detailed description describe various embodiments and areintended to provide an overview or framework for understanding thenature and character of the subject matter described and claimed herein.The accompanying drawings are included to provide a furtherunderstanding of the various embodiments, and are incorporated into andconstitute a part of this specification. The drawings illustrate thevarious embodiments described herein, and together with the descriptionserve to explain the principles and operations of the subject matterdescribed and claimed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic section view of a gas turbine engine including anelectrical machine, according to one or more embodiments shown anddescribed herein;

FIG. 2 is a diagrammatic view of a heat recovery system for use in thegas turbine engine of FIG. 1 , according to one or more embodimentsshown and described herein;

FIG. 3 is a diagrammatic view of another embodiment of a heat recoverysystem for use in the gas turbine engine of FIG. 1 , according to one ormore embodiments shown and described herein;

FIG. 4 is a schematic section view of the gas turbine engine of FIG. 1 ,according to one or more embodiments shown and described herein;

FIG. 5 is a more detailed, schematic section view of the gas turbineengine of FIG. 1 , according to one or more embodiments shown anddescribed herein;

FIG. 6 is a schematic section view of an outlet guide vane assembly foruse in the gas turbine engine of FIG. 5 , according to one or moreembodiments shown and described herein;

FIG. 7 is a schematic section view of the outlet guide vane assembly ofFIG. 5 , according to one or more embodiments shown and describedherein;

FIG. 8 is a schematic section view of another embodiment of an outletguide vane assembly, according to one or more embodiments shown anddescribed herein;

FIG. 9 is a schematic section view of another embodiment of a gasturbine engine, according to one or more embodiments shown and describedherein;

FIG. 10 is a schematic section view of another embodiment of a gasturbine engine, according to one or more embodiments shown and describedherein;

FIG. 11 is a schematic section view of another embodiment of a gasturbine engine, according to one or more embodiments shown and describedherein;

FIG. 12 is a schematic section view of the outlet guide vane assembly ofFIG. 10 , according to one or more embodiments shown and describedherein;

FIG. 13 is a diagrammatic view of an outlet guide vane assemblyconnected to a turbine rear frame, according to one or more embodimentsshown and described herein;

FIG. 14 is a diagrammatic view of an outlet guide vane assemblyconnected to a turbine rear frame, according to one or more embodimentsshown and described herein;

FIG. 15 is a diagrammatic view of an outlet guide vane assemblyconnected to a turbine rear frame, according to one or more embodimentsshown and described herein;

FIG. 16 is a diagrammatic view of an outlet guide vane assemblyconnected to a turbine rear frame, according to one or more embodimentsshown and described herein;

FIG. 17 is a diagrammatic view of an outlet guide vane assemblyconnected to a turbine rear frame, according to one or more embodimentsshown and described herein;

FIG. 18 is a diagrammatic view of an outlet guide vane assemblyconnected to a turbine rear frame, according to one or more embodimentsshown and described herein;

FIG. 19 is a diagrammatic view of an outlet guide vane assemblyconnected to a turbine rear frame, according to one or more embodimentsshown and described herein;

FIG. 20 is a diagrammatic side view of an outlet guide vane thatincludes surface enhancement features, according to one or moreembodiments shown and described herein;

FIG. 21 is a diagrammatic end view of the outlet guide vane of FIG. 20 ,according to one or more embodiments shown and described herein;

FIG. 22 is a diagrammatic side view of an outlet guide vane thatincludes surface enhancement features, according to one or moreembodiments shown and described herein;

FIG. 23 is a diagrammatic end view of the outlet guide vane of FIG. 22 ,according to one or more embodiments shown and described herein;

FIG. 24 is a diagrammatic side view of an outlet guide vane thatincludes surface enhancement features, according to one or moreembodiments shown and described herein;

FIG. 25 is a diagrammatic end view of the outlet guide vane of FIG. 24 ,according to one or more embodiments shown and described herein;

FIG. 26 is a diagrammatic side view of an outlet guide vane thatincludes surface enhancement features, according to one or moreembodiments shown and described herein;

FIG. 27 is a diagrammatic end view of the outlet guide vane of FIG. 26 ,according to one or more embodiments shown and described herein;

FIG. 28A is a diagrammatic end view of a surface enhancement feature,according to one or more embodiments shown and described herein;

FIG. 28B is a diagrammatic end view of another surface enhancementfeature, according to one or more embodiments shown and describedherein;

FIG. 28C is a diagrammatic end view of another surface enhancementfeature, according to one or more embodiments shown and describedherein;

FIG. 28D is a diagrammatic end view of another surface enhancementfeature, according to one or more embodiments shown and describedherein;

FIG. 29 is a diagrammatic side view of an outlet guide vane thatincludes surface enhancement features, according to one or moreembodiments shown and described herein;

FIG. 30 is a diagrammatic side view of an outlet guide vane thatincludes surface enhancement features, according to one or moreembodiments shown and described herein;

FIG. 31 is a diagrammatic side view of an outlet guide vane thatincludes surface enhancement features, according to one or moreembodiments shown and described herein;

FIG. 32 is a diagrammatic side section view illustrating surfaceenhancement features in operation, according to one or more embodimentsshown and described herein;

FIG. 33 is a diagrammatic side view of an outlet guide vane thatincludes surface enhancement features, according to one or moreembodiments shown and described herein;

FIG. 34 is a diagrammatic side view of an outlet guide vane thatincludes surface enhancement features, according to one or moreembodiments shown and described herein;

FIG. 35 is a diagrammatic side view of an outlet guide vane thatincludes multiple fluid passageways, according to one or moreembodiments shown and described herein;

FIG. 36 is a diagrammatic side view of an outlet guide vane thatincludes multiple fluid passageways, according to one or moreembodiments shown and described herein;

FIG. 37 is a diagrammatic side view of an outlet guide vane thatincludes multiple fluid passageways, according to one or moreembodiments shown and described herein;

FIG. 38 is a diagrammatic end view of a fluid passageway of an outletguide vane, according to one or more embodiments shown and describedherein;

FIG. 39 is a diagrammatic end view of a fluid passageway of an outletguide vane, according to one or more embodiments shown and describedherein;

FIG. 40 is a diagrammatic end view of a fluid passageway of an outletguide vane, according to one or more embodiments shown and describedherein;

FIG. 41 is a diagrammatic end view of a fluid passageway of an outletguide vane, according to one or more embodiments shown and describedherein;

FIG. 42 is a diagrammatic section view of a fluid passageway of anoutlet guide vane, according to one or more embodiments shown anddescribed herein;

FIG. 43 is a diagrammatic section view of a fluid passageway of anoutlet guide vane, according to one or more embodiments shown anddescribed herein;

FIG. 44 is a diagrammatic section view of a fluid passageway of anoutlet guide vane, according to one or more embodiments shown anddescribed herein;

FIG. 45 is a diagrammatic section view of a fluid passageway of anoutlet guide vane, according to one or more embodiments shown anddescribed herein; and

FIG. 46 is a diagrammatic section view of a fluid passageway of anoutlet guide vane, according to one or more embodiments shown anddescribed herein.

DETAILED DESCRIPTION

Embodiments described herein are generally directed to gas turbineengines that include heat recovery systems. The gas turbine engines mayinclude a compressor section and a turbine section arranged in serialflow order and together defining a core airflow path that leads to anexhaust airflow path out of the engine. A rotary member, such as ashaft, spool, etc., is rotatable with at least portions of thecompressor section and turbine section. An electrical machine may beembedded within the gas turbine engines. The electrical machine may berotatable with the rotary member and positioned coaxially with therotary member at least partially inward of the core airflow path along aradial direction of the gas turbine engines. The electrical machine maybe an electric generator that is driven by the rotary member.

The gas turbine engines include a heat recovery system that collectsheat from one or more locations using a fluid that is at a coolertemperature, such as a thermal transport fluid. As examples, the heatrecovery system may collect heat from the exhaust airflow path and/orthe electrical machine. The heat recovery system may be integrated intoexisting structural components of the gas turbine engines, such asoutlet guide vanes, that are formed to be suitable structures to carryheat exchange passageways therethrough and achieve heat recovery.

Referring to FIG. 1 , an exemplary gas turbine engine 10 may beconfigured for wing or fuselage mounting on an aircraft. In someembodiments, the gas turbine engine 10 may also be used to providepower. The gas turbine engine 10 includes a fan section 12 including afan 14, a compressor section 16 and a turbine section 18. The fansection 12, compressor section 16 and turbine section 18 may include oneor more rotor disks 20 that include rotor blades extending radiallytherefrom. Air is drawn into the gas turbine engine 10 and acceleratedby the fan 14. The air, or at least a portion thereof, is compressed inthe compressor section 16 and is delivered to a combustion chamber wherethe air is mixed with fuel and combusted thereby generating hotcombustion gases. The combustion gases pass through a turbine section18, which extracts mechanical work from the combustion gases to causethe attached compressor section 16 to turn and thereby further compressthe upstream air to produce a self-sustaining process. The combustiongas is exhausted through a nozzle section 22.

The gas turbine engine 10 defines an axial direction A that extendsparallel to a longitudinal centerline 23, a radial direction R thatextends perpendicular to the axial direction A, and a circumferentialdirection C that extends about the axial direction A. The gas turbineengine 10 includes the fan section 12 and a core section 24 that islocated downstream of the fan section 12 in the axial direction.

The gas turbine engine 10 includes a tubular core cowl 30 that defines,at least in part, an annular inlet 32. The core cowl 30 encases, inserial flow relationship, the compressor section 16 including a boosteror low pressure (LP) compressor 34 and a high pressure (HP) compressor36, a combustion section 38 that includes the combustion chamber, theturbine section 18 including a high pressure (HP) turbine 40 and a lowpressure (LP) turbine 42, and the jet exhaust nozzle section 22. Thecompressor section 16, combustion section 38, and turbine section 18together define a core airflow path 44 extending from the annular inlet32 through the LP compressor 34, HP compressor 36, combustion section38, and HP turbine 40. A first shaft or spool 45 drivingly connects theHP turbine 40 to the HP compressor 36. A second shaft or spool 48drivingly connects the LP turbine 42 to the LP compressor 34 and the fan14.

The fan section 12 includes the fan 14 having a plurality of fan blades46 coupled to a disk 49 in a spaced apart manner. The fan blades 46extend outward from disk 49 generally along the radial direction R. Thedisk 49 is covered by rotatable front hub 50 that is aerodynamicallycontoured to promote an air flow through the plurality of fan blades 46.The exemplary fan section 12 includes an annular fan casing or outernacelle 52 that circumferentially surrounds the fan 14 and/or at least aportion of the core section 24. The outer nacelle 52 is supportedrelative to the core section 24 by a plurality ofcircumferentially-spaced struts that also serve as outlet guide vanes54. A downstream section 56 of the outer nacelle 52 extends over anouter portion of the core cowl 30 to define a bypass airflow passage 58therebetween.

The gas turbine engine 10 includes an electrical machine 60 that isrotatable with the fan 14 and is located within a tail cone 65. Theelectrical machine 60 is an electric generator co-axially mounted to androtatable with the second shaft 48. In other embodiments, an axis of theelectrical machine 60 may be offset radially from the axis of the secondshaft 48 and further may be oblique to the axis of the second shaft 48,such that the electrical machine 60 may be positioned at any suitablelocation at least partially inward of the core airflow path 44. In someembodiments, the electrical machine 60 may be rotatable with the firstshaft 45.

The gas turbine engine 10 depicted in FIG. 1 is provided by way ofexample only. In other exemplary embodiments the gas turbine engine 10may be replaced with other types of gas turbine engines utilizing anembedded electrical machine without loss of clarity. Examples include aturboprop engine, a turbojet engine, an open rotor, or inducted fanengine.

Referring to FIGS. 2 and 3 , diagrammatic heat recovery systems areillustrated where heat is captured and used in different manners.Referring first to FIG. 2 , the heat recovery system 100 may include awaste heat recovery heat exchanger 102 that is a heat source heatexchanger for capturing heat for a particular area or component of thegas turbine engine 10. As will be described in greater detail below, thewaste heat recovery heat exchanger 102 may be formed by outlet guidevanes. In this example, the waste heat recovery heat exchanger 102 isdirectly integrated with a fuel delivery system 104 of the gas turbineengine 10. The fuel delivery system 104 provides fuel to the combustionsection 38 that is located between the HP compressor 36 and HP turbine40. The fuel is delivered from the fuel delivery system 104, through thewaste heat recovery heat exchanger 102 for pre-heating the fuel and thendelivered to the combustion section 38. Because the fuel is combusted inthe combustion section 38, pre-heating the fuel using the waste heatrecovery heat exchanger 102 can improve the efficiency of the combustionprocess.

Referring to FIG. 3 , another example of a heat recovery system 110including a waste heat recovery heat exchanger 112 that is integratedinto a fuel delivery system 114 indirectly through a thermal transportbus 116 is shown. The thermal transport bus 116 includes a heat exchangefluid flowing therethrough. A pump 118 is provided in the thermaltransport bus 116 for generating a flow of the heat exchange fluidthrough the thermal transport bus 116. The pump 118 may be a rotary pumpincluding an impeller, or may be any other suitable pump. The pump 118may be powered by an electric motor, or be in mechanical communicationwith and powered by one of the shafts 45 and 48 via an accessory gearbox120.

A fuel flow rate control 122 may include any number of pumps and nozzlesfor controlling delivery of fuel to the combustion section 38. In FIG. 3, the fuel flow rate control 122 is shown separately from fuel system124 because the fuel flow rate control 122 is used to deliver heat tothe fuel (e.g., via a heat sink heat exchanger) rather than directlythrough the waste heat recovery heat exchanger 112 as in FIG. 2 . Theheated fuel is then provided to the combustion section 38. A heat sinkheat exchanger 125 may be used to cool the heat exchange fluid upstreamof the pump 118.

Referring to FIG. 4 , a more detailed, cross-section view of the gasturbine engine 10 including heat recovery system 100 is illustrated. Theexemplary gas turbine engine 10 includes the core cowl 30 that encasesthe compressor section 16 including the LP compressor 34 (FIG. 1 ) andthe HP compressor 36, the combustion section 38 and the turbine section18 including the HP turbine 40 and the LP turbine 42. The outer nacelle52 defines the bypass airflow passage 58 with the core cowl 30. Theoutlet guide vane 54 supports the outer nacelle 52 relative to the corecowl 30.

The compressor section 16, the combustion section 38 and the turbinesection 18 together define at least part of the core airflow path 44.The fuel delivery system 104 provides a fuel flow to the combustionsection 38. The exemplary fuel delivery system 104 may generally includeone or more fuel nozzles 130 that are configured to provide a mixture offuel and air to the combustion chamber 132, as well as a fuel pump 134and fuel lines 136. The fuel pump 134 may provide fuel flow through thefuel lines 136 from a fuel source to the fuel nozzles 130.

As used herein, the terms “heat source” and “heat sink” describe a heatexchange relationship relative to the heat recovery system depending onwhether the heat exchange relationship is providing heat to the heatrecovery system or removing heat from the heat recovery system,respectively. For example, a heat source heat exchange relationshiprefers to a heat exchange relationship where heat is provided to theheat recovery system through thermal communication between the heatrecovery system and a heat source. As used herein, the term “thermalcommunication” refers to two or more systems being in relatively closeproximity to each other to enable an effective heat transfer between thesystems, e.g., a heated fluid contained within a non-insulated pipesubmerged in a cold fluid. A heat sink heat exchange relationship refersto a heat exchange relationship where heat is removed from the heatrecovery system.

Referring also to FIG. 5 , the waste heat recovery heat exchanger 102 isin a heat source heat exchange relationship with the fuel of the fueldelivery system 104. As can be seen, the fuel line 136 extends to a fuelpassageway 140 that is formed within an outlet guide vane 142 at adownstream end of the LP turbine 42. In some embodiments, a cold fuelpassageway 140 may be provided through one of the outlet guide vanes 142and a heated fuel passageway 144 may be provided through an adjacentoutlet guide vane that receives fuel from the cold fuel passageway 140.

As an example, FIG. 6 diagrammatically illustrates an outlet guide vaneassembly 146 that may or may not be a structural part of a turbine rearframe 150 (FIG. 5 ). The outlet guide vane assembly 146 includes aplurality of the outlet guide vanes 142 that are spaced-apart from oneanother in the circumferential direction within the core airflow path44. Each outlet guide vane 142 of at least a plurality of the outletguide vanes 142 includes either a heated fuel passageway 144 or a coldfuel passageway 140. It should be noted that the terms “heated” and“cold” are relative to maximum fuel temperatures within the passageways140 and 144 as, for example, fuel in the cold fuel passageway 140 may beheated, but not heated to a temperature that is higher than a maximumfuel temperature in the heated fuel passageway 144. In some embodiments,the cold fuel passageway 140 may be insulated to reduce heat transfer tofuel in the cold fuel passageway 140. Further, the fuel passageways 140and 144 are illustrated as being straight in the radial direction;however, the fuel passageways 140 and 144 may follow any suitable path,such as serpentine, wave-forms or even irregular passageways depending,at least in part, on the type of engine, the shape of the guide vanes,desired amount of heat exchange, etc.

Each outlet guide vane 142 includes an outer end 148 located at an outerguide vane support 151, an inner end 152 located at an inner guide vanesupport 154 and opposite sides 156 and 158. Referring briefly to FIG. 7, the sides 156 and 158 may together form the shape of a fin that mayhave multiple functions, one being to transfer heat from the coreairflow path 44 and then to transfer heat to the fuel in the heated fuelpassageway 144. Another function may be to guide the airflow as theairflow exits the gas turbine engine 10. In some embodiments, the shapesof the outlet guide vanes 142 may be non-turning or low-turning that arealigned with the turbine airflow exit angle thereby having littleinfluence on airflow direction. In some embodiments, the shape of theoutlet guide vanes 142 may be suitable to change or turn the turbineairflow exit angle. In this regard, these outlet guide vanes 142 may beconsidered turning outlet guide vanes 142. Whether turning ornon-turning, the outlet guide vanes 142 may be sized, shaped andconfigured to transfer heat from the heated air passing by the outletguide vanes 142 through the core airflow path 44 to fuel in the fuelpassageways 140 and 144 in order to pre-heat the fuel.

In FIG. 7 , the outlet guide vanes 142 are all of about the same lengthin the axial A direction, which can have a greater effect on the airflowdirection between the outlet guide vanes 142. Referring to FIG. 8 ,another embodiment of outlet guide vanes 162 is illustrated whereadjacent outlet guide vanes 162 a and 162 b are of different lengths,which can have a greater effect on heat exchange effectiveness. In thisexample, the outlet guide vanes 162 a are of relatively longer lengthand the outlet guide vanes 162 b are of relatively shorter length andthe outlet guide vanes 162 a. The shorter length of the outlet guidevanes 162 b can reduce an amount of area of the shorter length guidevanes 162 b exposed to the adjacent outlet guide vanes 162 a that canhave an impact on fuel temperature in cold fuel passageway 164 a. Theshorter length of the outlet guide vanes 162 b can also reduce an amountof material or distance between the heated fuel passageway 164 b and thesurrounding heated air compared to cold fuel passageway 164 a. In someembodiments, the cold fuel passageways 164 a may be insulated.

Referring again to FIG. 6 , the cold fuel passageways 140 may be fluidlycoupled to the fuel line 136 of the fuel delivery system 104 (FIG. 4 )at the outer end 148. In this regard, relatively cold fuel is providedto the cold fuel passageways 140. Each cold fuel passageway 140 may befluidly connected to a heated fuel passageway 144 by a connectingconduit 168. The connecting conduit 168 may be any suitable structurethat fluidly connects the fuel passageways 140 and 144. In someembodiments, the connecting conduit 168 may also be formed of a materialthat is suitable for transferring heat from the heated air to the fuelas the fuel enters the heated fuel passageway 144. The heated fuelpassageways 144 may be coupled to the fuel line 136 of the fuel deliverysystem 104 (FIG. 4 ) at the outer end 148. In this regard, heated fuelis provided to the combustion section 38.

As can be appreciated, the heat exchange relationship between the outletguide vanes 142 may be referred to as a heat source heat exchangerelationship as heat is being provided to the fuel as the fuel travelsalong the cold and heated fuel passageways 140 and 144. The heat sourceheat exchange relationship is being provided by the outlet guide vanes142 themselves, as opposed to a separately formed heat exchanger, withtheir integrated fuel passageways 140 and 144 extending therethrough. Insome embodiments, the fuel passageways 140 and 144 may be formed as anintegral and monolithic part of the outlet guide vanes 142. For example,three-dimensional printing may be used to form the outlet guide vanes142 and their associated fuel passageways 140 and 144. Rather than fuel,a thermal transfer fluid may pass through the passageways fortransferring heat to the fuel system as discussed and shown withreference to FIG. 3 .

Referring again to FIG. 5 , the gas turbine engine 10 may include theelectrical machine 60. The electrical machine 60 is disposed in an aftportion 172 of the gas turbine engine 10 and may be releasably mountedto the turbine rear frame 150 using a rear flange coupling 173 of theturbine rear frame 150 and a support structure 175 of the electricalmachine 60. The electrical machine 60 may also be releasably connectedto the LP shaft 48 at a shaft coupling 177. The aft portion 172 isdisposed axially downstream the core section 174 of the gas turbineengine 10.

The electrical machine 60 may be or include an electric generator thatconverts mechanical energy (e.g., generated from exhaust gases generatedin the core section 174) produced by the gas turbine engine 10 intoelectrical energy that may be used to power electrical devices of thegas turbine engine 10 or components disposed elsewhere on an aircraftincorporating the gas turbine engine 10. Positioning the electricalmachine 60 in the aft portion 172 of the gas turbine engine 10 canrender the electrical machine 60 accessible for maintenance, repair, andreplacement and can facilitate removal of the electrical machine 60 ifneeded. The electrical machine 60 may be integrated into the gas turbineengine 10 via the releasable couplings 173 and 177 that may be removedwithout invasively disassembling the entirety of the gas turbine engine10, such as without removing the gas turbine engine 10 from a wing of anaircraft.

Positioning the electrical machine 60 in the aft portion 172 providesaccessibility, but can create additional design considerations for thegas turbine engine 10. Exhaust gases generated via the core section 174can be at relatively high temperatures (e.g., in excess of approximately700° C. or more in various embodiments), which renders cooling theelectrical machine 60 beneficial. Additionally, the aft portion 172 ofthe gas turbine engine 10 may not be directly connected to an aircraftincorporating the gas turbine engine 10 (e.g., the gas turbine engine 10may be connected to a wing of an aircraft via a pylon extending from theouter nacelle 52 (FIG. 1 ) disposed radially outward from the coresection 174. Given this, to provide the electrical power generated viathe electrical machine 60 to other portions of the aircraft, theelectrical power is routed through the gas turbine engine 10.

In view of the foregoing, generator services 180 may be routed throughthe turbine rear frame 150. The generator services 180 may include alubrication conduit and a plurality of electrical connectors (e.g.,power cables) that conductively connect the electrical machine 60 to aconverter. The lubrication conduit may carry a lubricant, such as oil tothe electrical machine 60. The oil may be used as part of the coolingsystem and used to cool the electrical machine and then be carried away,for example, back through the generator services 180.

The electrical connectors connect the electrical machine 60 to theconverter. For example, the electrical machine 60 may generate analternating current (“AC”) power signal from mechanical energy in thespinning LP shaft 48, which electrical power is routed to the converter(located in the forward part of the engine) via the generator services180. The converter may generate a DC voltage from the AC power signalfor communication to alternative locations on the aircraft (e.g., via anelectrical communications bus). The generator services 180 may include aplurality of sets of electrical connectors, with each set of electricalconnectors including a number of electrical connectors that correspondto the number of phases in the AC power signal generated via theelectrical machine 60. The number of sets of electrical connectors ofthe generator services 180 may vary depending on the implementation.Incorporating a number of different sets of electrical connectors in thegenerator services 180 can provide electrical connection redundanciesthat facilitate provision of the AC power signal to the converter evenif one of the sets of the electrical connectors fails during operation.

Referring to FIG. 9 , another embodiment of a heat recovery system 200may be incorporated into a gas turbine engine 210 that is similar to thegas turbine engine 10 of FIG. 5 . The gas turbine engine 210 includes aturbine rear frame 212 and an outlet guide vane assembly 214 thatincludes a plurality of outlet guide vanes 216. The outlet guide vaneassembly 214 may be releasably coupled to the turbine rear frame 212using a rear flange coupling 218 as above with FIG. 5 , or the outletguide vane assembly 214 may be coupled directly to the turbine rearframe 212 and be a structural, load bearing part of the turbine rearframe 212.

The heat recovery system 200 includes a thermal transport bus 220 thatincludes a thermal transport fluid that is configured to flowtherethrough. The outlet guide vanes 216 include either a heated fluidpassageway 222 or a cold fluid passageway 224 that are fluidly connectedto the thermal transport bus 220 such that the thermal transport fluidflows therethrough.

In this embodiment, the heat recovery system 200 may also be part of acooling system that is used to cool an electrical machine 226 that islocated in aft portion 228 of the gas turbine engine 210. As can beseen, the thermal transport bus 220 extends radially toward and awayfrom the electrical machine 226. The electrical machine 226 may be partof an electrical machine assembly 230 that also includes a supportstructure 232 that connects the electrical machine 226 to both theturbine rear frame 212 and an LP shaft 234. The support structure 232,for example, may include an outer segment 236 that connects a stator ofthe electrical machine to the fixed turbine rear frame 212 and an innersegment 238 that connects a rotor to the LP shaft 234 that rotates therotor relative to the stator.

The thermal transport bus 220 may extend alongside and be mounted to thesupport structure 232 with a cold portion 240 of the thermal transportbus 220 passing through at least portions of the support structure 232and/or the electrical machine 226. The thermal transport fluid absorbsheat from the electrical machine 226, which can control the temperatureof the electrical machine during use. The heated thermal transport fluidmay then return via a heated portion 242 and then through the heatedfluid passageway 222 for delivering the heated thermal transport fluidto another system, such as the fuel delivery system 114 of FIG. 3 ,where the waste heat can be used to transfer heat to another system.

Referring to FIG. 10 , another embodiment of a heat recovery system 300may be incorporated into a gas turbine engine 310 that is similar to thegas turbine engine 210 of FIG. 9 . The gas turbine engine 310 includes aturbine rear frame 312 and an outlet guide vane assembly 314 thatincludes a plurality of outlet guide vanes 316. The outlet guide vaneassembly 314 may again be releasably coupled to the turbine rear frame312 using a rear flange coupling 318, or the outlet guide vane assembly314 may be coupled directly to the turbine rear frame 312 and be astructural, load bearing part of the turbine rear frame 312.

As above, a thermal transport bus 320 includes a thermal transport fluidthat is configured to flow therethrough. The outlet guide vanes 316include either a heated fluid passageway 322 or a cold fluid passageway324 that are fluidly connected to the thermal transport bus 320 suchthat the thermal transport fluid flows therethrough.

In this embodiment, generator services 326 extend through passageways inthe outlet guide vanes 316. For example, the generator services 326 mayextend through insulated passages in the outlet guide vanes 316 that aredifferent from the heated and cold fluid passageways 322 and 324. Thethermal transport bus 320 and the generator services 326 extend radiallytoward an electrical machine 328. A support structure 340 connects theelectrical machine 328 to both the turbine rear frame 312 and an LPshaft 342. The generator services 326 and the thermal transport bus 320may be mounted to the support structure 340. Electrical connections ofthe generator services 326 back to engine systems may be made outside ofcore airflow path 344 (e.g., in an outer cowl compartment) orconnections can be made in tail cone 346, below the outlet guide vanes316.

FIG. 11 illustrates an embodiment of a heat recovery system 400 that issimilar to the heat recovery system 300 of FIG. 10 . In this embodiment,an outlet guide vane assembly 402 is a structural component that isbolted directly to a turbine rear frame 404 without a rear flangecoupling. As above, a thermal transport bus 420 includes a thermaltransport fluid that is configured to flow therethrough. Outlet guidevanes 416 include a heated fluid passageway 422 or a cold fluidpassageway 424 and generator services 426 extend through passageways inthe outlet guide vanes 416. Electrical machine 428 may be accessiblethrough an access panel or the tail cone 430 along with the electricalmachine 428 may be removed as a unit.

FIG. 12 diagrammatically illustrates the outlet guide vane assembly 314that may or may not be part of the turbine rear frame 312. The outletguide vane assembly 314 includes the plurality of the outlet guide vanes316 that are spaced-apart from one another in the circumferentialdirection within the core airflow path. Each outlet guide vane 316 of atleast a plurality of the outlet guide vanes 316 includes either theheated fuel passageway 322 or a cold fluid passageway 324. The generatorservices 326 may include generator oil supply and return fluidpassageways 329 and 330 and electric connector passageway 332 and 334.In some embodiments, the passageways 324, 329, 330, 332 and 334 may beinsulated while the heated fluid passageway 322 may be formed of athermally conducting material. The cold fluid passageways 324 lead tothe electrical machine 328 to provide a cooling jacket 433, while theheated fluid passageways 322 direct the heated fluid away from theelectrical machine 328.

Referring now to FIG. 13 , an embodiment of an outlet guide vaneassembly 500 is illustrated diagrammatically. The outlet guide vaneassembly 500 is releasably mounted to a turbine rear frame 502 at mounts504. A bearing assembly 506 may be provided that allows for rotation ofturbine 508, LP shaft 510 and electrical machine 512 relative to theturbine rear frame 502. Cold and heated fluid passageways 514 and 515extend through outlet guide vanes 516 of the outlet guide vane assembly502 to take away heat from the electrical machine 512. The cold fluidpassageway 514 may be provided with insulation 513 of the outlet guidevane 516 to bring cool fluid to the electrical machine 512, then theheated fluid returns through heated fluid passageway 515, which may beuninsulated to facilitate heat transfer to the fluid.

In some embodiments, the turbine rear frame 502 may also include outletguide vanes 518 that may be turning or non-turning. Further, the outletguide vanes 516 of the outlet guide vane assembly may be either turningor non-turning, as described above. The size and shape of the outletguide vanes 516, 518 of the outlet guide vane assembly 500 and theturbine rear frame 502 may be selected to cooperate to change a flowangle of the heated air as the air passes by the outlet guide vanes 516,518.

Referring now to FIGS. 14-17 , a number of turbine rear frame and outletguide vane assemblies are illustrated. It should be noted that the shapeand scale of the guide vane assemblies described herein are not to scaleand are representative of a general shape of the guide vane assemblies.The turning guide vanes may have, for example, a leading edge that isless than 30 degrees relative to the airflow direction exiting theturbine section and a trailing edge that is less than five degreesrelative to the airflow direction. Various shapes, sizes and turningangles may be used depending on the particular engine architecture.Referring first to FIG. 14 , a non or low-turning turbine rear frame 520includes outlet guide vanes 522. The outlet guide vanes 522 are low ornon-turning in that they are arranged at about the same angle as theairflow exiting the turbine section. The outlet guide vanes 522 directthe heated air toward a turning outlet guide vane assembly 524 that islocated downstream of the outlet guide vanes 522 of the turbine rearframe 520. The outlet guide vane assembly 524 includes outlet guidevanes 526 that are arranged at an angle to the airflow exiting theturbine section to change or turn the direction of airflow. The outletguide vanes 526 of the outlet guide vane assembly 524 may include heatedand cold fluid passages, as discussed above.

Referring to FIG. 15 , a turning turbine rear frame 530 includes outletguide vanes 532. The outlet guide vanes 532 direct the heated air towarda low or non-turning outlet guide vane assembly 534 that is locateddownstream of the outlet guide vanes 532 of the turbine rear frame 530.The outlet guide vane assembly 534 includes outlet guide vanes 536 thatare arranged at an angle that is about the same as the airflow exitingthe turbine rear frame 530. The outlet guide vanes 536 of the outletguide vane assembly 534 may include heated and cold fluid passages, asdiscussed above.

Referring to FIG. 16 , a turning turbine rear frame 540 includes outletguide vanes 542. The outlet guide vanes 542 direct the heated air towarda low or non-turning outlet guide vane assembly 544 that is locatedbetween the outlet guide vanes 542 and inside of the turbine rear frame540. The outlet guide vane assembly 544 includes outlet guide vanes 546that are arranged at an angle that is about the same as the airflowexiting the turbine rear frame 540. The outlet guide vanes 546 of theoutlet guide vane assembly 544 may include heated and cold fluidpassages, as discussed above.

Referring to FIG. 17 , a turning outlet guide vane assembly 554 includesoutlet guide vanes 556. The outlet guide vanes 556 direct the heated airtoward a low or non-turning turbine rear frame 550 that is locateddownstream of the outlet guide vanes 556 of the outlet guide vaneassembly 554. The outlet guide vanes 556 of the outlet guide vaneassembly 54 may include heated and cold fluid passages, as discussedabove.

Referring to FIG. 18 (which is a same general turning/non-turningarrangement of FIG. 14 ), in some embodiments, an outlet guide vaneassembly 600 may be assembled with multiple packages of individual ormultiple vane modules 602. In some embodiments, the multiple vanemodules 602 may include multiple vane sets for a reduced integrationcomplexity and reduced number of modular sets. The vane modules 602 mayeach include multiple outlet guide vanes 604 a, 604 b that includeheated and cold fluid passages 606 and 608. The vane modules 602 areassembled to form the 360 degree outlet guide vane assembly 600. Eachvane module 602 can include quick disconnect links (represented by lines610) into a thermal transport bus and can be individually removable,e.g., for repair or replacement. In some embodiments, the outlet guidevane assembly 600 may be pre-assembled and then mounted to turbine rearframe 612 forming a turbine rear frame and heat exchanger assembly 614.The entire outlet guide assembly 600 may be flightline replaceable as aunit.

Referring to FIG. 19 , another embodiment of a turbine rear frame andheat exchanger assembly 620 includes a turbine rear frame 622 includingoutlet guide vanes 624 and outlet guide vane assembly 626 includingoutlet guide vanes 628. The outlet guide vanes 624 of the turbine rearframe 622 may be non or low-turning while the outlet guide vanes 628 maybe turning such that the outlet guide vanes 624 and 628 function intandem to change airflow direction. In contrast to the embodiment ofFIG. 18 , the outlet guide vanes 628 of the outlet guide vane assembly626 are all of substantially a same length in the axial direction. Theoutlet guide vanes 628 are arranged in two staggered rows 632 and 634such that outlet guide vanes 628 of row 632 have leading edges 636 thatare aligned in the circumferential C direction in front of leading edges638 of the outlet guide vanes 628 of row 634 that are also aligned inthe circumferential direction C. As above, the guide vanes 628 includeheated and cold fluid passages 640 and 642. The increased lengths of theoutlet guide vanes 628 can further enhance airflow control. Incombination with FIG. 7 and FIG. 18 , any arrangement of same/differentlength guide vanes and offset/aligned leading edges may be used.

Referring now to FIGS. 20 and 21 , various surface enhancement features,such as fins, dimples and ribs, may be provided on surfaces of theoutlet guide vanes to provide even more airflow and heat transfercapabilities. The surface enhancement features may be provided onsurfaces of any of the outlet guide vanes described herein. FIGS. 20 and21 illustrate a cross-sectional, partial view of an outlet guide vaneassembly 650 that includes outlet guide vanes 652 that include sidesurfaces 654 and 655 including fins 656 that are located between outerand inner guide vane supports 658 and 660. The fins 656 may have alength that is substantially the same as a length of the outlet guidevanes 652. In other embodiments, the fins 656 may have lengths that areless than the length of the outlet guide vanes 652. The fins 656 extendgenerally in the axial direction A, but may have other orientations, asdescribed below. An array of fins 656 is illustrated and the fins 656are spaced-apart in the radial direction R along a height of the outletguide vanes 652.

Fins may refer to structures that generally increase surface area of theside surfaces of the outlet guide vanes for increased heat transfer.Ribs may refer to shorter and/or thicker surface enhancement featuresthat may be used to increase heat transfer more by inducing turbulentflow across the outlet guide vanes. Dimples may refer to recesses intothe side surfaces that may be used to increase heat transfer more byinducing turbulent flow across the outlet guide vanes. Introducingturbulent flow can encourage mixing of layers of air, which can improveheat transfer. These surface enhancement features all increase surfacearea against which the air flows.

FIGS. 22-32 illustrate additional surface area enhancement features ofthe outlet guide vanes described herein. Referring first to FIGS. 22 and23 , ribs 662 are illustrated that extend along heights of outlet guidevanes 664 in the radial direction R. The ribs 662 may have a height inthe radial direction R that is substantially the same as a height of theoutlet guide vanes 664. In other embodiments, the ribs 662 may haveheights that are less than the heights of the outlet guide vanes 664.The ribs 662 extend generally in the radial direction R. An array ofribs 662 is illustrated and the ribs 662 are spaced-apart in the axialdirection A along a length of the outlet guide vanes 664.

Referring to FIGS. 24 and 25 , as another example, ribs 670 areillustrated that extend along both the heights and the lengths of outletguide vanes 672 in both axial and radial directions A and R. An array ofribs 670 is illustrated and the ribs 670 are spaced-apart in both theaxial and radial directions A and R. The ribs 670 may be inclined to theaxial direction at any suitable angle, such as 30 degrees, 45 degrees,60 degrees, between zero and 90 degrees, between 20 and 60 degrees, etc.

Referring to FIGS. 26 and 27 , ribs 674 are illustrated that extendalong both the heights and the lengths of outlet guide vanes 676 in bothaxial and radial directions A and R. In this embodiments, the ribs 674are arranged in a V-shaped pattern. An array of ribs 674 is illustratedand the ribs 670 are spaced-apart in both the axial and radialdirections A and R. The ribs 674 may be inclined to the axial directionat any suitable angle, such as 30 degrees, 45 degrees, 60 degrees,between zero and 90 degrees, between 20 and 60 degrees, etc.

FIGS. 28A-28D illustrate fins and ribs of various cross-sectionalshapes. Suitable shapes include rectangles, triangles, etc. Othersuitable shapes may be used, such as wavy shapes or irregular shapes. Insome embodiments, the surface enhancement features may formed as amonolithic part and of the same material as the outlet guide vanes. Forexample, additive manufacturing may be used to form the surfaceenhancement

Fins and ribs may be surface enhancement features that project outwardfrom the surfaces of the outlet guide vanes. Surfaces of the outletguide vanes may be provided with surface enhancement features thatproject inward from the surfaces, such as dimples. Referring to FIG. 29, an outlet guide vane 680 includes dimples 682 that are arranged overat least one surface 684 of the outlet guide vanes 680. The dimples 682are formed as recesses in the surface 684 and are also provided togenerate more turbulent flow to increase heat transfer.

The dimples 682 may be any suitable shape, such as round, ovular,rectangular, etc. In the illustrated example, the dimples 682 are ovalhaving an elongated, round shape. In FIG. 29 , the elongated direction Dof the dimples 682 extends in the axial direction A. In FIG. 30 , theelongated direction D of dimples 686 is aligned with the radialdirection R. In FIG. 31 , the elongated direction D of dimples 688 isinclined to the axial direction A, such as 30 degrees, 45 degrees, 60degrees, between 40 and 60 degrees, etc. Other configurations arepossible, such as a V-shaped elongated direction arrangement.

Referring to FIG. 32 , operation of the dimples 682 is illustrateddiagrammatically. As represented by arrow 690, airflow without influenceof the dimples 682 tends to be relatively laminar. Represented by arrow692, air entering the dimples 682 tends to introduce more turbulent flowthere air of the various layers tend to mix.

Referring to FIGS. 33 and 34 , in some embodiments, outlet guide vanes700 and 702 may be provided with surface enhancement features 704 and706 that alters a trailing edge 708 and 710 geometry of the outlet guidevanes 700 and 702. For example, the surface enhancement features mayinclude fins 704 and 706 that are provided at the trailing edges 708 and710. The fins 704 and 706 may be provided with (FIG. 34 ) or without(FIG. 33 ) the surface enhancement features discussed above, such asfins 712, ribs and/or dimples. The surface enhancement features 704 and706 may be used for noise augmentation to alter a sound profile of theexhaust stream.

Referring to FIGS. 35-37 , various fluid passage configurations may beformed depending on the desired fluid flow characteristics. For example,referring to FIG. 35 , an outlet guide vane 714 may be provided withmultiple fluid passages 716, 718, 720 and 722. In this example, thefluid passages 716, 718, 720 and 722 direct fluid all in the samedirection as indicated by arrows 723. In FIG. 36 , fluid passages 724and 726 direct fluid radially inward as indicated by arrows 725, whilefluid passages 728 and 730 direct fluid radially outward as indicated byarrows 727. Fewer or more fluid passages may be provided, such as shownby FIG. 37 that includes two fluid passageways 732 and 734, onepassageway 732 directing fluid radially inward and the other passageway734 directing fluid radially outward.

Referring now to FIGS. 38-41 , fluid passages 740, 742, 744 and 746 maybe provided with surface enhancement features 748, 750, 752 and 754,such as fins, dimples, ribs, dividers, etc. As can be seen, the passages740, 742, 744 and 746 themselves may be a predetermined cross-sectionalshape, such as round or rectangular. Referring to FIGS. 42 and 43 , thesurface enhancement features 748, 750, 752 and 754 may be provided apre-selected intervals (FIG. 42 ) or the entire length of the passageway740, 742, 744 and 746 (FIG. 43 ).

Referring to FIGS. 44 and 45 , surface enhancement features 760 and 762may act as turbulators to increase turbulence in fluid passages 764 and766. The surface enhancement features 760 and 762 may extend entirelyaround the fluid passages 764 and 766 360 degrees or they may extendonly partially around the fluid passages 764 and 766. In someembodiments, the surface enhancement features 762 may be staggered andalternate in a repeating fashion, such as shown by FIG. 45 . FIG. 46shows another embodiment that includes a fluid passage 770 that includessurface enhancement features 772 in the form of dimples. The dimples 772can also be used to introduce turbulence in the fluid flow.

The above-described outlet guide vane assemblies provide an integratedheat exchanger structure that captures heat and can remove heat from theexhaust air stream and an electric machine. The waste heat can then beused to heat other systems, such a fuel of the fuel delivery system. Theoutlet guide vane assemblies can provide a line replaceable unit thatenables dispatch reliability. The generator lubricant and electricalconnectors can be segregated from the turbine rear frame which canisolate the system for repairability without disassembling theturbomachinery. Damaged vane modules can also be removed and replaced.Combining the generator cooling and waste heat removal into a singlecircuit can increase benefits of the thermal transport system. Theoutlet guide vanes of the outlet guide vane assembly can be used asturning elements behind a non-turning turbine rear frame, which canimprove overall flowpath losses. The thermal transport fluid can be usedto cool the generator using an independent pump after the engine is shutdown, which can improve thermal soakback effects on the generator. Theoutlet guide vane assembly, or parts thereof, can be removed with theturbine rear frame attached to the turbine casing and engine bearingsand sumps can be unaffected by the removal of the outlet guide vaneassembly.

As used herein, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to “a” component includes aspects having two or moresuch components, unless the context clearly indicates otherwise.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment. Itwill be further understood that the endpoints of each of the ranges aresignificant both in relation to the other endpoint, and independently ofthe other endpoint. The term “about” may include any values within tenpercent of a particular value, such as within five percent of aparticular value, such as within two percent of a particular value, suchas within one percent of a particular value.

Directional terms as used herein—for example up, down, right, left,front, back, top, bottom, upper, lower, —are made only with reference tothe figures as drawn and are not intended to imply absolute orientationunless otherwise expressly stated. The terms “axial” and “longitudinal”both refer to a direction that is parallel to a centerline the gasturbine engine, while “radial” refers to a direction perpendicular tothe longitudinal direction. The terms “tangential” and “circumferential”refer to a direction mutually perpendicular to both the radial andlongitudinal directions. The terms “forward” or “front” refer to alocation upstream in airflow passing through or around a componentduring operation, and the terms “aft” or “rear” refer to a locationdownstream during operation. These directional terms are used merely forconvenience in the description and also do not require a particularorientation of the structures described thereby.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order, nor that with any apparatus specificorientations be required. Accordingly, where a method claim does notactually recite an order to be followed by its steps, or that anyapparatus claim does not actually recite an order or orientation toindividual components, or it is not otherwise specifically stated in theclaims or description that the steps are to be limited to a specificorder, or that a specific order or orientation to components of anapparatus is not recited, it is in no way intended that an order ororientation be inferred, in any respect. This holds for any possiblenon-express basis for interpretation, including: matters of logic withrespect to arrangement of steps, operational flow, order of components,or orientation of components; plain meaning derived from grammaticalorganization or punctuation, and; the number or type of embodimentsdescribed in the specification.

Further aspects are provided by the subject matter in the followingclauses:

1. A gas turbine engine comprising: a fan located at a forward portionof the gas turbine engine; a compressor section and a turbine sectionarranged in serial flow order, the compressor section and the turbinesection together defining a core airflow path; a rotary member rotatablewith at least a portion of the compressor section and with at least aportion of the turbine section; and an outlet guide vane assemblycomprising multiple outlet guide vanes located in an exhaust airflowpath downstream of the turbine section, the multiple outlet guide vanesbeing spaced-apart circumferentially from each other over an angularrange of about 360 degrees, and each multiple outlet guide vane defininga radial extent; wherein at least one of the multiple outlet guide vanescomprises a cold fluid passageway extending at least partially radiallytherethrough and another of the multiple guide vanes comprises a heatedfluid passageway extending at least partially radially therethroughwhich the fluid coolant flows and receives heat from exhaust airflowfrom the core airflow path.

2. The gas turbine engine of any preceding clause, wherein the at leastone of the multiple outlet guide vanes comprises multiple fluidpassageways extending at least partially radially therethrough.

3. The gas turbine engine of any preceding clause further comprising aturbine rear frame that supports the turbine section, the turbine rearframe comprising the outlet guide vane assembly.

4. The gas turbine engine of any preceding clause further comprising aturbine rear frame that supports the turbine section, the outlet guidevane assembly connected to the turbine rear frame.

5. The gas turbine engine of any preceding clause, wherein the turbinerear frame comprises multiple outlet guide vanes located in the exhaustairflow path downstream of the turbine section that are spaced-apartcircumferentially from each other about 360 degrees.

6. The gas turbine engine of any preceding clause, wherein the multipleoutlet guide vanes of the turbine rear frame are low or non-turning andthe multiple outlet guide vanes of the outlet guide vane assembly areturning.

7. The gas turbine engine of any preceding clause, wherein the multipleoutlet guide vanes of the turbine rear frame are turning and themultiple outlet guide vanes of the outlet guide vane assembly are low ornon-turning.

8. The gas turbine engine of any preceding clause further comprising anelectrical machine coupled to the rotary member and located at leastpartially inward of the core airflow path in a radial direction.

9. The gas turbine engine of any preceding clause further comprising athermal transport bus comprising a thermal transport fluid, the thermaltransport bus providing the thermal transport fluid to the cold fluidpassageway and the heated fluid passageway.

10. The gas turbine engine of any preceding clause, wherein the thermaltransport bus extends from the cold fluid passageway and the heatedfluid passageway to the electrical machine to carry heat away from theelectrical machine during operation.

11. The gas turbine engine of any preceding clause, wherein the coldfluid passageway and the heated fluid passageway are connected to a fueldelivery system, wherein fuel is directed through the cold and heatedfluid passageways.

12. The gas turbine engine of any preceding clause, wherein the outletguide vane assembly comprises multiple vane modules that are assembledtogether, each vane module including at least one of the multiple outletguide vanes of the outlet guide vane assembly.

13. The gas turbine engine of any preceding clause, wherein the multipleoutlet guide vanes of the outlet guide vane assembly have differentlengths.

14. The gas turbine engine of any preceding clause, wherein the multipleoutlet guide vanes of the outlet guide vane assembly have substantiallythe same length.

15. The gas turbine engine of any preceding clause the at least one ofthe multiple outlet guide vanes comprises a surface enhancement featurethat increases a surface area of a side surface of the outlet guidevane.

16. The gas turbine engine of any preceding clause, wherein the surfaceenhancement feature projects outwardly from the side surface.

17. The gas turbine engine of any preceding clause, wherein the surfaceenhancement feature is a recess in the side surface.

18. The gas turbine engine of any preceding clause, wherein one or bothof the cold fluid passageway and the heated fluid passageway comprises asurface enhancement feature that extends into the one or both of thecold fluid passageway and the heated fluid passageway.

19. The gas turbine engine of any preceding clause, wherein the at leastone of the multiple outlet guide vanes comprises a surface enhancementfeature located at a trailing edge of the at least one of the multipleoutlet guide vanes.

20. A method comprising: removably attaching an outlet guide vaneassembly to a turbine rear frame of a gas turbine engine, the outletguide vane assembly comprising: multiple outlet guide vanes located inan exhaust airflow path downstream of the turbine section, the multipleoutlet guide vanes being spaced-apart circumferentially from each otherover an angular range of about 360 degrees, and each multiple outletguide vane defining a radial extent, wherein at least one of themultiple outlet guide vanes comprises a cold fluid passageway extendingat least partially radially therethrough through which a fluid coolantflows and another of the multiple guide vanes comprises a heated fluidpassageway extending at least partially radially therethrough throughwhich the fluid coolant flows and receives heat from exhaust airflowfrom a core airflow path; and delivering the fluid coolant through thecold fluid passageway and then the heated fluid passageway, the fluidcoolant receiving heat from exhaust airflow from the core airflow pathas the fluid coolant is directed through the heated fluid passageway.

21. The method of any preceding clause further comprising a fueldelivery system delivering fuel to the cold fluid passageway andreceiving fuel from the heated fluid passageway.

22. The method of any preceding clause further comprising a thermaltransport bus delivering a thermal transport fluid to the cold fluidpassageway and receiving thermal transport fluid from the heated fluidpassageway.

23. The method of any preceding clause, wherein the gas turbine enginefurther comprises an electrical machine coupled to a rotary member andlocated at least partially inward of a core airflow path of the gasturbine engine in a radial direction, the method further comprisingdelivering the thermal transport fluid to the electrical machine therebytransferring heat from the electrical machine to the thermal transportfluid.

24. The method of any preceding clause further comprising assemblingmultiple vane modules together to form the outlet guide vane assembly,each vane module including at least one of the multiple outlet guidevanes of the outlet guide vane assembly.

25. The method of any preceding clause further comprising individuallyremoving one or more of the multiple vane modules from the outlet guidevane assembly with the remaining multiple guide vane modules remainingconnected to the turbine rear frame.

26. The method of any preceding clause further comprising replacing theone or more of the multiple vane modules with one or more different vanemodules.

27. The method of any preceding clause, wherein the at least one of themultiple outlet guide vanes comprises a surface enhancement feature thatincreases a surface area of a side surface of the outlet guide vane.

28. The method of any preceding clause, wherein the surface enhancementfeature projects outwardly from the side surface.

29. The method of any preceding clause, wherein the surface enhancementfeature is a recess in the side surface.

30. A gas turbine engine comprising: a fan located at a forward portionof the gas turbine engine; a compressor section and a turbine sectionarranged in serial flow order, the compressor section and the turbinesection together defining a core airflow path; a rotary member rotatablewith at least a portion of the compressor section and with at least aportion of the turbine section; and an outlet guide vane assemblycomprising multiple outlet guide vanes located in an exhaust airflowpath downstream of the turbine section that are spaced-apartcircumferentially from each other about 360 degrees; wherein one or moreoutlet guide vane comprises a surface enhancement feature that increasesa surface area of a side surface of the outlet guide vane.

31. The gas turbine engine of any preceding clause, wherein the outletguide vane comprises a cold fluid passageway extending radiallytherethrough.

32. The gas turbine engine of any preceding clause, wherein another ofthe multiple guide vanes comprises a heated fluid passageway extendingradially therethrough in fluid communication with the cold fluidpassageway.

33. The gas turbine engine of any preceding clause, wherein one or bothof the cold fluid passageway and the heated fluid passageway comprises asurface enhancement feature that extends into the one or both of thecold fluid passageway and the heated fluid passageway.

34. The gas turbine engine of any preceding clause, wherein the surfaceenhancement feature projects outwardly from the side surface.

35. The gas turbine engine of any preceding clause, wherein the surfaceenhancement feature is a recess in the side surface.

36. The gas turbine engine of any preceding clause, wherein the outletguide vane comprises multiple surface enhancement features.

37. The gas turbine engine of any preceding clause, wherein the multiplesurface enhancement features are arranged in an array where adjacentsurface enhancement features are spaced-apart.

30. A gas turbine engine comprising: a compressor section and a turbinesection arranged in serial flow order, the compressor section and theturbine section together defining a core airflow path; a rotary memberrotatable with at least a portion of the compressor section and with atleast a portion of the turbine section; a turbine rear frame comprisingfirst outlet guide vanes located in an exhaust airflow path downstreamof the turbine section, the first outlet guide vanes being spaced-apartcircumferentially from each other over an angular range of about 360degrees, and each first outlet guide vane defining a radial extent; andan outlet guide vane assembly comprising second outlet guide vaneslocated in the exhaust airflow path adjacent the first outlet guidevanes, the second outlet guide vanes being spaced-apartcircumferentially from each other over an angular range of about 360degrees, and each second outlet guide vane defining a radial extent;wherein one or both of the first outlet guide vanes and the secondoutlet guide vanes is turning thereby altering a flow direction ofexhaust airflow from the exhaust airflow path.

31. The gas turbine engine of claim 30, wherein the first outlet guidevanes are low or non-turning arranged at about a same angle as theexhaust airflow and the second outlet guide vanes are turning.

32. The gas turbine engine of claim 30, wherein the first outlet guidevanes are turning and the second outlet guide vanes are low ornon-turning arranged at about a same angle as the exhaust airflow.

33. The gas turbine engine of claim 30, wherein both of the first outletguide vanes and the second outlet guide vanes are turning.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the embodiments describedherein without departing from the spirit and scope of the claimedsubject matter. Thus, it is intended that the specification cover themodifications and variations of the various embodiments described hereinprovided such modification and variations come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A gas turbine engine comprising: a fan located ata forward portion of the gas turbine engine; a compressor section and aturbine section arranged in serial flow order, the compressor sectionand the turbine section together defining a core airflow path; a rotarymember rotatable with at least a portion of the compressor section andwith at least a portion of the turbine section; and an outlet guide vaneassembly comprising multiple outlet guide vanes located in an exhaustairflow path downstream of the turbine section, the multiple outletguide vanes being spaced-apart circumferentially from each other over anangular range of about 360 degrees, and each multiple outlet guide vanedefining a radial extent; wherein at least one of the multiple outletguide vanes comprises a cold fluid passageway extending at leastpartially radially therethrough through which a fluid coolant flows awayfrom a thermal transport bus connected to a source of the liquid coolantand another of the multiple guide vanes comprises a heated fluidpassageway extending at least partially radially therethrough throughwhich the fluid coolant flows and receives heat from exhaust airflowfrom the core airflow path and returns to the thermal transport bus, thecold fluid passageway and heated fluid passageway are connected togetherforming a closed fluid passageway through the cold fluid passageway,away from the thermal transport bus and through the heated fluidpassageway back to the thermal transport bus.
 2. The gas turbine engineof claim 1, wherein the at least one of the multiple outlet guide vanescomprises multiple fluid passageways extending at least partiallyradially therethrough.
 3. The gas turbine engine of claim 1 furthercomprising a turbine rear frame that supports the turbine section, theturbine rear frame comprising the outlet guide vane assembly.
 4. The gasturbine engine of claim 1 further comprising a turbine rear frame thatsupports the turbine section, the outlet guide vane assembly connectedto the turbine rear frame.
 5. The gas turbine engine of claim 4, whereinthe cold fluid passageway and the heated fluid passageway are connectedtogether by a connecting conduit forming a turn between the cold fluidpassageway and the heated fluid passageway.
 6. The gas turbine engine ofclaim 1, wherein the multiple outlet guide vanes of the turbine rearframe are low or non-turning and the multiple outlet guide vanes of theoutlet guide vane assembly are turning.
 7. The gas turbine engine ofclaim 5, wherein the multiple outlet guide vanes of the turbine rearframe are turning and the multiple outlet guide vanes of the outletguide vane assembly are low or non-turning.
 8. The gas turbine engine ofclaim 1 further comprising an electrical machine coupled to the rotarymember and located at least partially inward of the core airflow path ina radial direction.
 9. The gas turbine engine of claim 8, wherein thefluid coolant comprises a thermal transport fluid.
 10. The gas turbineengine of claim 9, wherein the thermal transport bus extends from thecold fluid passageway and the heated fluid passageway to the electricalmachine to carry heat away from the electrical machine during operation.11. The gas turbine engine of claim 1, wherein the cold fluid passagewayand the heated fluid passageway are connected to a fuel delivery system,wherein the fluid coolant comprises fuel that is directed through thecold and heated fluid passageways.
 12. The gas turbine engine of claim1, wherein the outlet guide vane assembly comprises multiple vanemodules that are assembled together, each vane module including at leastone of the multiple outlet guide vanes of the outlet guide vaneassembly.
 13. The gas turbine engine of claim 1, wherein the multipleoutlet guide vanes of the outlet guide vane assembly have differentlengths.
 14. The gas turbine engine of claim 1, wherein the multipleoutlet guide vanes of the outlet guide vane assembly have substantiallythe same length.
 15. The gas turbine engine of claim 1 the at least oneof the multiple outlet guide vanes comprises a surface enhancementfeature that increases a surface area of a side surface of the outletguide vane.
 16. The gas turbine engine of claim 15, wherein the surfaceenhancement feature projects outwardly from the side surface.
 17. Thegas turbine engine of claim 15, wherein the surface enhancement featureis a recess in the side surface.
 18. The gas turbine engine of claim 1,wherein one or both of the cold fluid passageway and the heated fluidpassageway comprises a surface enhancement feature that extends into theone or both of the cold fluid passageway and the heated fluidpassageway.
 19. The gas turbine engine of claim 1, wherein the at leastone of the multiple outlet guide vanes comprises a surface enhancementfeature located at a trailing edge of the at least one of the multipleoutlet guide vanes.
 20. A method comprising: removably attaching anoutlet guide vane assembly to a turbine rear frame of a gas turbineengine, the outlet guide vane assembly comprising: multiple outlet guidevanes located in an exhaust airflow path downstream of a turbinesection, the multiple outlet guide vanes being spaced-apartcircumferentially from each other over an angular range of about 360degrees, and each multiple outlet guide vane defining a radial extent;wherein at least one of the multiple outlet guide vanes comprises a coldfluid passageway extending at least partially radially therethroughthrough which a fluid coolant flows away from a thermal transport busconnected to a source of the liquid coolant and another of the multipleguide vanes comprises a heated fluid passageway extending at leastpartially radially therethrough through which the fluid coolant flowsand receives heat from exhaust airflow from a core airflow path andreturns to the thermal transport bus, the cold fluid passageway andheated fluid passageway are connected together forming a closed fluidpassageway through the cold fluid passageway, away from the thermaltransport bus and through the heated fluid passageway back to thethermal transport bus; and delivering the fluid coolant through the coldfluid passageway and then the heated fluid passageway, the fluid coolantreceiving heat from exhaust airflow from the core airflow path as thefluid coolant is directed through the heated fluid passageway.
 21. Themethod of claim 20 further comprising a fuel delivery system deliveringfuel to the cold fluid passageway and receiving fuel from the heatedfluid passageway, the fluid coolant comprising the fuel.
 22. The methodof claim 20, wherein the fluid coolant comprises a thermal transportfluid, the gas turbine engine further comprising a thermal transport busdelivering a thermal transport fluid to the cold fluid passageway andreceiving thermal transport fluid from the heated fluid passageway. 23.The method of claim 22, wherein the gas turbine engine further comprisesan electrical machine coupled to a rotary member and located at leastpartially inward of a core airflow path of the gas turbine engine in aradial direction, the method further comprising delivering the thermaltransport fluid to the electrical machine thereby transferring heat fromthe electrical machine to the thermal transport fluid.
 24. The method ofclaim 20 further comprising assembling multiple vane modules together toform the outlet guide vane assembly, each vane module including at leastone of the multiple outlet guide vanes of the outlet guide vaneassembly.
 25. The method of claim 24 further comprising individuallyremoving one or more of the multiple vane modules from the outlet guidevane assembly with the remaining multiple guide vane modules remainingconnected to the turbine rear frame.
 26. The method of claim 25 furthercomprising replacing the one or more of the multiple vane modules withone or more different vane modules.
 27. The method of claim 20, whereinthe at least one of the multiple outlet guide vanes comprises a surfaceenhancement feature that increases a surface area of a side surface ofthe outlet guide vane.
 28. The method of claim 27, wherein the surfaceenhancement feature projects outwardly from the side surface.
 29. Themethod of claim 27, wherein the surface enhancement feature is a recessin the side surface.